Op zondag 11 september 2022 om 03:06:43 UTC+2 schreef DD'eDeN aka note/nickname/alas_my_loves:
https://phys.org/news/2022-09-worldwide-woody.html
Thanks!
The evolution of insular woodiness
Alexander Zizka cs 2022
PNAS 119 (37) e2208629119
doi org/10.1073/pnas.2208629119
IW (the evolution of woodiness in plant spp that inhabit islands) is the most conspicuous aspect of island floras, cf.
- flightlessness in birds,
- dwarfism/gigantism in mammals,
yet scientific evidence on IW has been too fragmented to understand its distribution & evolutionary origins.
Here, we identify >1000 insular woody spp resulting from at least 175 independent evolutionary transitions on 31 different archipelagos around the world.
In combination with global data on island spp composition, climate & environment conditions, we test multiple long-standing hypotheses re. the origins of insular woodiness:
best correlated with the occurrence of insular woody spp across all islands are - the absence of herbivores,
- traits related to drought stress .
Abstract
IW is one of the most iconic features of island floras.
Since pioneering work by Darwin & Wallace, a nr of drivers of IW have been proposed, e.g.
1) competition for sunlight requiring plants with taller & stronger woody stems,
2) drought, favoring woodiness to safeguard root-to-shoot water transport. Alternatively, IW may be the indirect result of increased life-span, related to 3) a favorable aseasonal climate and/or
4) a lack of large native herbivores.
However, information on the occurrence of IW is fragmented, hampering tests of these potential drivers.
Here, we identify 1097 insular woody spp on 375 islands, and infer at least 175 evolutionary transitions on 31 archipelagos, concentrated in 6 angiosperm families.
Structural equation models reveal:
the insular woody spp richness on oceanic islands correlates with
- a favorable aseasonal climate, followed by
- increased drought &
- island isolation (approximating competition).
When continental islands are also included, reduced herbivory pressure by large native mammals, increased drought & island isolation are most relevant.
Our results
- illustrate different trajectories leading to rampant convergent evolution toward IW,
- emphasize archipelagos as natural laboratories of evolution, where similar abiotic or biotic conditions replicated evolution of similar traits.
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